Production of additive mixtures

ABSTRACT

The invention relates to a method for producing additive mixtures for fuel oils by mixing at least two additive components in a dynamic mixer or a lamination mixer. The invention further relates to additive mixtures obtained by said method and fuel oil compositions containing said additive mixtures.

The present invention relates to a process for producing additive mixtures for fuel oils by mixing at least two additive components in a dynamic mixer or in a lamination mixer. The present invention further relates to the additive mixtures obtainable via this process and to fuel oil compositions which comprise such additive mixtures.

Mineral oils and crude oils which comprise paraffinic waxes exhibit a significant deterioration in the flow properties as the temperature is lowered. The cause of this lies in the crystallization, which sets in from the temperature of the cloud point, of relatively long-chain paraffins which form large platelet-shaped wax crystals. These wax crystals have a spongelike structure and lead to inclusion of other fuel constituents in the crystal structure.

The occurrence of these crystals leads to a deterioration in the flow properties of the mineral oils and crude oils, as a result of which disruption can occur in the extraction, transport, storage and/or use of the oils. For instance, when the oils are transported through pipelines, in winter in particular, there can be deposits on the pipe walls and even complete blockage. In the case of mineral oils, there may be blockage and conglutination of fuel filters in motor vehicle engines (fuel filters) and boiler, which prevents reliable metering of the fuels and, under some circumstances, complete stoppage of the fuel supply occurs. At temperatures below the pour point (PP), there is finally no longer any flow of fuel.

To alleviate these problems, additives which frequently consist of a combination of nucleators with the actual cold flow improvers (CFIs) have already been added in low concentrations to the mineral oils and crude oils for some time. Nucleators are substances which generate crystal nuclei which promote the formation of ultra small crystals. Cold flow improvers have similar crystallization properties to the paraffins present in mineral oil or crude oil, but prevent their growth. Moreover, wax antisettling additives (WASAs) which prevent the settling of the ultra small crystals in the oils are added to the crude oils and mineral oils. Frequently, mixtures of CFIs and WASAs are also used, which are also referred to as WAFIs (wax antisettling flow improvers).

These cold flow improvers are usually added as additive packages to the mineral oils and crude oils. These additive packages generally comprise, as well as the cold flow improvers, at least one solvent and frequently also further additives, for example detergent additives, dispersants, defoamers and others.

Since the composition of the crude oils and mineral oils varies owing to the different origin of the crude oils and the different operating conditions in the refineries, more or less tailored additive packages have to be provided for the individual oils. It is therefore of great economic significance to be able to provide the additive packages in a rapid, flexible process with reliably reproducible results. At the same time, the additive packages should not only have good functional properties, for example good cold flow-improving properties, but also good handling properties, for example should be easily incorporable into the oil.

In general, additive mixtures are produced batchwise, i.e. one or more active ingredient components and a solvent are metered successively into a vessel and then mixed by stirring or pumped circulation. A disadvantage is the long time required for the charging, heating and mixing. The achievement of sufficient homogeneity requires, especially in the case of mixing of active ingredients and solvents of different viscosity, prolonged stirring or circulation over several hours to days. The desired or required mixing temperature is generally established only slowly according to the amounts of the components to be mixed and their temperatures, and also the heating output set. Frequently, it deviates significantly from the mean, for example at the metering point of the components and at the heating elements, such that the temperature profile is reproducible only with difficulty during the mixing operation. Especially in the case of rapid heating at the heating elements, for example the vessel jacket, significant overheating can occur, which, in the course of the subsequent storage of the additive packages, can lead to the sedimentation of the suspended active ingredients or even to their thermal decomposition.

In addition, the flowability or pumpability of dispersions of these partly crystalline polymers is in many cases dependent on the mixing conditions. Thus, partially or incompletely molten formulations of partly crystalline polymers with solvents and optionally further active ingredients lead to dispersions with a high intrinsic pour point (PP), whereas completely melted polymers give rise to dispersions with a significantly lower pour point. The controlled establishment of a constant pour point of the formulation produced, which is important for the product handling, is thus possible in the case of batchwise mixing only with a high level of additional technical complexity and/or time demands, for example resulting from heating or cooling of the finished mixture.

EP-A-1405896 describes a continuous process for producing additive mixtures for mineral oils and mineral oil distillates, in which a cold flow improver is mixed with a further cold flow improver or a solvent in a static mixer at a defined temperature. Static mixers are mixing systems in which the energy required for the mixing operation is introduced by the mixing components. They frequently comprise fixed internals and bring about mixing of the components through exploitation of their flow energy.

The additive mixtures obtained with this mixing process no longer have many of the disadvantages of the additive mixtures which are obtained with the older batchwise mixing processes; the mixing process is also significantly faster. However, some handling properties of the additive mixtures obtained by the process of EP-A-1405896, for example the lower mixing temperature and the filterability, are still unsatisfactory. Moreover, it is virtually impossible with static mixers to completely and homogeneously mix components with very different viscosities or else components which are present in the mixture in very different proportions.

It was therefore an object of the present invention to provide additive mixtures for fuel oils which, as well as good functional properties (i.e. properties for which these additives are actually added to the fuel oils, for example cold flow-improving properties), have improved handling properties compared to the prior art additive mixtures, for example a relatively low minimum mixing temperature (LMT) and/or a better filterability of the fuel oil additized with them. Moreover, they should also have an improved storage stability. In addition, it should also be possible to compose the additive mixtures homogeneously from components which have a very different viscosity and/or are to be present in very different proportions in the mixture.

The minimum mixing temperature is an important economic factor for the blending of the fuel oils with the additives, since the lower the minimum mixing temperature of an additive is, the less the fuel oil has to be heated in order to be able to mix the additive in homogeneously. The minimum mixing temperature is thus important especially for those refineries which mix the additives unheated into fuel oils or mix additives into unheated fuel oils. When the minimum mixing temperature of the additive is high, there may be filter problems after unheated mixing.

The filterability of additized fuel oils is a measure of the solubility and miscibility of the additive used into the fuel oil. In the context of the present invention, the filterability is determined by means of the SEDAB method described below. A good filterability is obtained when the additive added is readily miscible into or soluble in the fuel oil.

A prolonged storage stability is likewise an important economic factor, since it allows the production of the products from stock, such that it is possible to cope more easily, for example, with peaks in demand, or to allow production runs (for individual additive compositions) to run for longer and hence in a more economically viable manner, without the product quality falling unacceptably in the course of prolonged storage.

The object is achieved by a process for producing additive mixtures for fuel oils, in which at least two components of the additive mixture are mixed in a mixer selected from dynamic mixers and lamination mixers.

The statements made below regarding suitable and preferred embodiments of the process according to the invention, of the inventive additive mixture and of the inventive fuel oil composition, especially of the components to be mixed, of the fuel oils and of the mixers and of the mixing conditions, apply both taken alone and in any conceivable combination with one another.

In dynamic mixers, the energy input required for the mixing operation is effected by the mixer itself. These mixers comprise moving mixing units or a moving vessel. The most common are so-called rotor-stator systems with a fixed housing (stator) and a rotating machine part (rotor). In the intermediate spaces between rotor and stator, the rotating motion of the rotor forms a shear flow which is frequently but not necessarily turbulent. In this shear flow, the components are mixed by virtue of new phase interfaces constantly being created between them.

In principle, however, all types of dynamic mixers are suitable for the process according to the invention.

The dynamic mixers are preferably selected from rotor mills, toothed ring dispersing machines, inline dispersing machines, colloid mills, corundum disc mills, scraped heat exchangers, mixing pumps and ultrasound homogenizers. The dynamic mixers are more preferably selected from rotor-stator systems, for example from rotor mills, toothed ring dispersing machines, colloid mills, corundum disc mills and mixing pumps. In particular, the dynamic mixers are selected from toothed ring dispersing machines and mixing pumps.

A further means of generating particularly good mixtures is the use of lamination mixers. Lamination mixers are a specific type of nondynamic mixers, in which the fluid streams to be mixed are fanned out into a multitude of thin lamellae or films, and these lamellae are subsequently merged with one another in an alternating manner, such that diffusion and secondary flows result in very rapid mixing. The fanning out of the incoming streams of the pure mixture component can be effected, for example, by means of flow dividers which divide the incoming streams into lamellar layers or films of adjustable thickness. By virtue of an appropriate three-dimensional arrangement, alternating layering of the lamellar pure substance streams is brought about at the exit from the flow divider, and, according to the design, may have a two-dimensional structure in mutually adjacent planes or as concentric ring streams. As a result of diffusion, a substance concentration balance then takes place between the layers, and hence mixing of the components.

The selection of suitable mixers depends upon factors including the combination of the particular mixing components and their use amount, and can be determined by the person skilled in the art in the individual case, for example by means of simple preliminary tests.

Preference is given to using a dynamic mixer. With regard to suitable and preferred dynamic mixers, reference is made to the remarks above.

In the process according to the invention, the components can also be mixed in several mixers which are arranged in any sequence, arrangement or combination, at least one of the mixers being a dynamic mixer or a lamination mixer. The remaining mixers may be any mixer types, for example one or more further dynamic mixers and/or lamination mixers and/or static mixers. The mixers may be arranged in series arrangement or in a combined series and parallel arrangement.

In the process according to the invention, the components are preferably mixed, however, in a single mixer.

The components are preferably mixed at elevated temperature, preferably at least 30° C., for example at from 30 to 180° C. or from 30 to 150° C. or from 30 to 100° C., more preferably at least 50° C., for example at from 50 to 180° C. or at from 50 to 150° C. or at from 50 to 100° C., and especially at least 70° C., for example at from 70 to 180° C. or at from 70 to 150° C. or at from 70 to 100° C. The different components may have different entrance temperatures at the mixer.

The desired mixing temperature can be established either before or during the mixing operation. The temperature is generally established before the mixing operation by bringing the components to be mixed to the desired temperature shortly before they are fed into the mixer, or by maintaining them at the desired temperature in a reservoir vessel. When the temperature can fall during the supply, the components are sensibly first brought to a higher temperature which falls to the desired mixing temperature during the supply. The temperature is established during the mixing operation generally by means of heating elements which are installed on or in the mixer, for example through a jacket or a tube bundle. The mixing temperature is preferably adjusted to the desired temperature or a somewhat higher temperature before the mixing operation by heating the components to be mixed.

The components can be supplied into the mixer by all customary methods, for example by direct addition of all components in pure form or by addition of suitable premixtures. When premixtures are used, they can be formed in a separate step or, as mentioned above, be produced in a mixer connected upstream of the actual (dynamic or lamination) mixer.

In the process according to the invention, the establishment of a homogenous mixture with the desired product properties generally takes at most 200 seconds, preferably at most 120 seconds, more preferably at most 60 seconds and in particular at most 45 seconds, especially at most 30 seconds. These time data are the mean mixing time, i.e. the mean duration of residence of the components in the mixing zone.

The process according to the invention can be configured as a batchwise, semibatchwise or continuous process. However, it is preferably a continuous process.

In the continuous process, the mass throughput is preferably from 0.001 to 200 t/h, more preferably from 0.01 to 100 t/h and especially from 1 to 100 t/h.

In the continuous process variant, a dynamic mixer or a lamination mixer is generally supplied continuously with the components to be mixed via suitable supply lines, and the components can be supplied to the mixer, as already stated, either by direct addition of all components in pure form or by addition of suitable premixtures. The pure components are preferably brought to the desired mixing temperature or to a temperature somewhat above the desired mixing temperature by suitable measures before the entry into the mixer. Since the mixing duration/residence time is generally very short, it is generally unnecessary in steady-state continuous operation to heat the mixer. On completion of mixing, the mixture is then discharged continuously from the mixer.

After the mixing operation, it is favorable to cool the mixture formed before discharge from the mixing system. Any customary cooling apparatus is suitable, especially that for indirect cooling, such as heat exchangers. This achieves the effect that the mixture remains stable at ambient temperature.

In a preferred embodiment of the invention, the process according to the invention serves to produce CFI additive packages. Accordingly, the at least two components of the additive mixture comprise

(i) at least one cold flow improver and (ii) at least one solvent.

Component (i) and component (ii) are used in a weight ratio of preferably from 1:99 to 99:1, more preferably from 10:90 to 90:10 and especially from 20:80 to 80:20.

The cold flow improvers may be all customary prior art cold flow improvers. However, the cold flow improver is preferably selected from

-   (a) copolymers of ethylene with at least one further ethylenically     unsaturated monomer; -   (b) comb polymers; -   (c) polyoxyalkylenes; -   (d) polar nitrogen compounds; -   (e) sulfocarboxylic acids or sulfonic acids or derivatives thereof; -   (f) poly(meth)acrylic esters; -   (g) alkylphenol-aldehyde resins;     and mixtures thereof.

In the copolymers of ethylene with at least one further ethylenically unsaturated monomer (a), the monomer is preferably selected from alkenylcarboxylic esters, (meth)acrylic esters, styrene, styrene derivatives and olefins.

Suitable olefins are, for example, those having from 3 to 10 carbon atoms and having from 1 to 3, preferably having 1 or 2, especially having one carbon-carbon double bond(s). In the latter case, the carbon-carbon double bond may be arranged either terminally (α-olefin) or internally. However, preference is given to α-olefins, particular preference to α-olefins having from 3 to 6 carbon atoms, such as propene, 1-butene, 1-pentene and 1-hexene.

Suitable styrene derivatives are C₁-C₄-alkyl-substituted styrenes such as α-methylstyrene, 2-, 3- or 4-methylstyrene, 2-, 3- or 4-ethylstyrene, 2-, 3- or 4-propyl-styrene, 4-isopropylstyrene, 2-, 3- or 4-n-butylstyrene, 4-isobutylstyrene, 4-tert-butylstyrene, 2,4- or 2,6-dimethylstyrene and 2,4- or 2,6-diethylstyrene. Among these, preference is given to α-methylstyrene, 2-, 3- or 4-methylstyrene and 2,4- or 2,6-dimethylstyrene and especially 2-, 3- or 4-methylstyrene and 2,4- or 2,6-dimethyl-styrene.

Suitable (meth)acrylic esters are, for example, esters of (meth)acrylic acid with C₁-C₂₀-alkanols, especially with methanol, ethanol, propanol, isopropanol, n-butanol, sec-butanol, isobutanol, tert-butanol, pentanol, hexanol, heptanol, octanol, 2-ethylhexanol, nonanol, decanol, 2-propylheptanol, undecanol, lauryl alcohol, tridecanol, myristyl alcohol, pentadecanol, palmityl alcohol, heptadecanol, stearyl alcohol, nonadecanol and eicosanol.

Suitable alkenyl carboxylates are, for example, the vinyl and propenyl esters of carboxylic acids having from 2 to 20 carbon atoms, whose hydrocarbon radical may be linear or branched. Among these, preference is given to the vinyl esters. Among the carboxylic acids with a branched hydrocarbon radical, preference is given to those whose branch is in the α position to the carboxyl group, the α carbon atom more preferably being tertiary, i.e. the carboxylic acid being a so-called neocarboxylic acid. However, the hydrocarbon radical of the carboxylic acid is more preferably linear.

Examples of suitable alkenyl carboxylates are vinyl acetate, vinyl propionate, vinyl butyrate, vinyl neopentanoate, vinyl hexanoate, vinyl neononanoate, vinyl neodecanoate and the corresponding propenyl esters, preference being given to the vinyl esters. A particularly preferred alkenyl carboxylate is vinyl acetate.

More preferably, the ethylenically unsaturated monomer is selected from alkenyl carboxylates. Even more preferably, the ethylenically unsaturated monomer comprises vinyl acetate.

Also suitable are copolymers which comprise two or more different alkenyl carboxylates in copolymerized form, which differ in the alkenyl function and/or in the carboxylic acid group. One of the alkenyl carboxylates is preferably vinyl acetate. Likewise suitable are copolymers which, as well as the alkenyl carboxylate(s), comprise at least one olefin and/or at least one (meth)acrylic ester and/or styrene and/or at least one styrene derivative in copolymerized form. Among these, preference is given to terpolymers, i.e. copolymers which, as well as an alkenyl carboxylate, which is preferably vinyl acetate, comprise an olefin or a (meth)acrylic ester or styrene or a styrene derivative in copolymerized form. With regard to suitable and preferred olefins, alkenyl carboxylates, (meth)acrylic esters and styrene derivatives, reference is made to the above remarks.

The at least one ethylenically unsaturated monomer is copolymerized in the copolymer in a total amount of preferably from 1 to 30 mol %, more preferably of from 1 to 25 mol % and especially of from 5 to 20 mol %, based on the overall copolymer.

The copolymer (a) preferably has a number-average molecular weight Mn of from 500 to 20 000, more preferably from 750 to 15 000.

Comb polymers (b) are, for example, those described in “Comb-Like Polymers. Structure and Properties”, N. A. Platé and V. P. Shibaev, J. Poly. Sci. Macromolecular Revs. 8, pages 117 to 253 (1974). Among those described there, suitable comb polymers are, for example, those of the formula II

in which

D is R¹⁷, COOR¹⁷, OCOR¹⁷, R¹⁸, OCOR¹⁷ or OR¹⁷, E is H, CH₃, D or R¹⁸, G is H or D,

J is H, R¹⁸, R¹⁸COOR¹⁷, aryl or heterocyclyl,

K is H, COOR¹⁸, OCOR¹⁸, OR¹⁸ or COOH,

L is H, R¹⁸, COOR¹⁸, OCOR¹⁸, COOH or aryl, where R¹⁷ is a hydrocarbon radical having at least 10 carbon atoms, preferably having from 10 to 30 carbon atoms, R¹⁸ is a hydrocarbon radical having at least one carbon atom, preferably having from 1 to 30 carbon atoms, m is a molar fraction in the range from 1.0 to 0.4 and n is a molar fraction in the range from 0 to 0.6.

Preferred comb polymers are obtainable, for example, by copolymerization of maleic anhydride or fumaric acid with another ethylenically unsaturated monomer, for example with an α-olefin or an unsaturated ester, such as vinyl acetate, and subsequent esterification of the anhydride or acid function with an alcohol having at least 10 carbon atoms. Further preferred comb polymers are copolymers of α-olefins and esterified comonomers, for example esterified copolymers of styrene and maleic anhydride or esterified copolymers of styrene and fumaric acid. Also suitable are mixtures of comb polymers. Comb polymers may also be polyfumarates or polymaleates. Homo- and copolymers of vinyl ethers are also suitable comb polymers.

Suitable polyoxyalkylenes (c) are, for example, polyoxyalkylene esters, ethers, ester/ethers and mixtures thereof. The polyoxyalkylene compounds preferably comprise at least one, more preferably at least two, linear alkyl group(s) having from 10 to 30 carbon atoms and a polyoxyalkylene group having a molecular weight of up to 5000. The alkyl group of the polyoxyalkylene radical preferably comprises from 1 to 4 carbon atoms. Such polyoxyalkylene compounds are described, for example, in EP-A-0 061 895 and in U.S. Pat. No. 4,491,455, which are hereby fully incorporated by reference. Preferred polyoxyalkylene esters, ethers and ester/ethers have the general formula III

R¹⁹[O—(CH₂)_(y)]_(x)O—R²⁰  (III)

in which R¹⁹ and R²⁰ are each independently R²¹, R²¹—CO—, R²¹—O—CO(CH₂)_(z)— or R²¹—O—CO(CH₂)_(z)—CO—, where R²¹ is linear C₁-C₃₀-alkyl, y is from 1 to 4, x is from 2 to 200, and z is from 1 to 4.

Preferred polyoxyalkylene compounds of the formula III in which both R¹⁹ and R²⁰ are R²¹ are polyethylene glycols and polypropylene glycols having a number-average molecular weight of from 100 to 5000. Preferred polyoxyalkylenes of the formula III in which one of the R¹⁹ radicals is R²¹ and the other is R²¹—CO— are polyoxyalkylene esters of fatty acids having from 10 to 30 carbon atoms, such as stearic acid or behenic acid. Preferred polyoxyalkylene compounds in which both R¹⁹ and R²⁰ are an R²¹—CO— radical are diesters of fatty acids having from 10 to 30 carbon atoms, preferably of stearic acid or behenic acid.

The polar nitrogen compounds (d), which are advantageously oil-soluble, may be either ionic or nonionic and preferably have at least one, more preferably at least 2, substituent(s) of the formula >NR²² in which R²² is a C₈-C₄₀-hydrocarbon radical. The nitrogen substituents may also be quaternized, i.e. be in cationic form. One example of such nitrogen compounds is that of ammonium salts and/or amides or imides which are obtainable by the reaction of at least one amine substituted with at least one hydrocarbon radical with a carboxylic acid having from 1 to 4 carboxyl groups or with a suitable derivative thereof. The amines preferably comprise at least one linear C₈-C₄₀-alkyl radical. Suitable primary amines are, for example, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tetradecylamine and the higher linear homologs. Suitable secondary amines are, for example, dioctadecylamine and methylbehenylamine. Also suitable are amine mixtures, in particular amine mixtures obtainable on the industrial scale, such as fatty amines or hydrogenated tallamines, as described, for example, in Ullmann's Encyclopedia of Industrial Chemistry, 6th edition, 2000 electronic release, “Amines, aliphatic” chapter. Acids suitable for the reaction are, for example, cyclohexane-1,2-dicarboxylic acid, cyclohexene-1,2-dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, naphthalenedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid and succinic acids substituted with long-chain hydrocarbon radicals.

A further example of polar nitrogen compounds is that of ring systems which bear at least two substituents of the formula -A-NR²³R²⁴ in which A is a linear or branched aliphatic hydrocarbon group which is optionally interrupted by one or more groups selected from O, S, NR³⁵ and CO, and R²³ and R²⁴ are each a C₉-C₄₀-hydrocarbon radical which is optionally interrupted by one or more groups selected from O, S, NR³⁵ and CO, and/or substituted by one or more substituents selected from OH, SH and NR³⁵R³⁶ where R³⁵ is C₁-C₄₀-alkyl which is optionally interrupted by one or more moieties selected from CO, NR³⁵, O and S, and/or substituted by one or more radicals selected from NR³⁷R³⁸, OR³⁷, SR³⁷, COR³⁷, COOR³⁷, CONR³⁷R³⁸, aryl or heterocyclyl, where R³⁷ and R³⁸ are each independently selected from H or C₁-C₄-alkyl; and R³⁶ is H or R³⁵.

A is preferably a methylene or polymethylene group having from 2 to 20 methylene units. Examples of suitable R²³ and R²⁴ radicals are 2-hydroxyethyl, 3-hydroxypropyl, 4-hydroxybutyl, 2-ketopropyl, ethoxyethyl and propoxypropyl. The cyclic system may be homocyclic, heterocyclic, fused polycyclic or nonfused polycyclic systems. The ring system is preferably carbo- or heteroaromatic, in particular carboaromatic. Examples of such polycyclic ring systems are fused benzoid structures such as naphthalene, anthracene, phenanthrene and pyrene, fused nonbenzoid structures such as azulene, indene, hydrindene and fluorene, nonfused polycycles such as diphenyl, heterocycles such as quinoline, indole, dihydroindole, benzofuran, coumarin, isocoumarin, benzo-thiophene, carbazole, diphenylene oxide and diphenylene sulfide, nonaromatic or partly saturated ring systems such as decalin, and three-dimensional structures such as α-pinene, camphene, bornylene, norbornane, norbornene, bicyclooctane and bicyclooctene.

A further example of suitable polar nitrogen compounds is that of condensates of long-chain primary or secondary amines with carboxyl group-comprising polymers.

The polar nitrogen compounds mentioned here are described in WO 00/44857 and also in the references cited therein, which are hereby fully incorporated by reference.

Suitable polar nitrogen compounds are also described, for example, in DE-A-198 48 621, DE-A-196 22 052 or EP-B 398 101, which are hereby incorporated by reference.

Preferred polar nitrogen compounds are ammonium salts and/or amides or imides which are obtainable by the reaction of at least one amine substituted by at least one hydrocarbon radical with a carboxylic acid having from 1 to 4 carboxyl groups or with a suitable derivative thereof. Among these, preference is given to ammonium salts and/or amides or imides of succinic acid substituted by a long-chain hydrocarbon radical, especially by a polyisobutyl radical.

Suitable sulfocarboxylic acids/sulfonic acids or their derivatives (e) are, for example, those of the general formula IV

in which Y is SO₃ ⁻(NR²⁵ ₃R²⁶)⁺, SO₃ ⁻(NHR²⁵ ₂R²⁶)⁺, SO₃ ⁻(NH₂R²⁵ ₂R²⁶), SO₃ ⁻(NH₃R²⁶) or SO₂NR²⁵R²⁶, X is Y, CONR²⁵R²⁷, CO₂ ⁻(NR²⁵ ₃R²⁷)⁺, CO₂ ⁻(NHR²⁵2R²⁷)⁺, R²⁸—COOR²⁷, NR²⁵COR²⁷, R²⁸OR²⁷, R²⁸OCOR²⁷, R²⁸R²⁷, N(COR²⁵)R²⁷ or Z⁻(NR²⁵ ₃R²⁷)⁺, where R²⁵ is a hydrocarbon radical, R²⁶ and R²⁷ are each alkyl, alkoxyalkyl or polyalkoxyalkyl having at least 10 carbon atoms in the main chain, R²⁸ is C₂-C₅-alkylene, Z⁻ is one anion equivalent and A and B are each alkyl, alkenyl or two substituted hydrocarbon radicals or, together with the carbon atoms to which they are bonded, form an aromatic or cycloaliphatic ring system.

Such sulfocarboxylic acids and sulfonic acids and their derivatives are described in EP-A-0 261 957, which is hereby fully incorporated by reference.

Suitable poly(meth)acrylic esters (f) are either homo- or copolymers of acrylic and methacrylic esters. Preference is given to copolymers of at least two different (meth)acrylic esters which differ in the esterified alcohol. The copolymer optionally comprises a further, different copolymerized olefinically unsaturated monomer. The weight-average molecular weight of the polymer is preferably from 50 000 to 500 000. A particularly preferred polymer is a copolymer of methacrylic acid and methacrylic esters of saturated C₁₄- and C₁₅-alcohols, in which the acid groups have been neutralized with hydrogenated tallamine. Suitable poly(meth)acrylic esters are described, for example, in WO 00/44857, which is fully incorporated herein by way of reference.

Suitable alkylphenol-aldehyde resins (g) are described, for example, in Römpp Chemie Lexikon, 9th edition, Thieme Verlag, 1988-1992, page 3352. They are oil-soluble polycondensation products of aliphatic aldehydes having generally from 1 to 4 carbon atoms, such as formaldehyde, acetaldehyde, propionaldehyde and butyraldehyde, especially formaldehyde, with phenols which bear 1 or 2 alkyl groups, preferably 1 alkyl group, having from 1 to 50, preferably from 1 to 20 and especially from 4 to 12 carbon atoms in the ortho or para position. The molecular weight of these polycondensates is generally in the range from 400 to 10 000, preferably from 400 to 5000.

The at least one cold flow improver preferably comprises at least one copolymer of ethylene with at least one further ethylenically unsaturated monomer (a). With regard to preferred copolymers, reference is made to the above remarks.

Also suitable are mixtures of copolymers (a) with at least one of the cold flow improvers (b) to (g).

In particular, the at least one cold flow improver (i) is a copolymer of ethylene with at least one further ethylenically unsaturated monomer (a), more preferably a copolymer of ethylene with at least one alkenyl carboxylate or a copolymer of ethylene with an alkenyl carboxylate and a (meth)acrylic ester or a copolymer of ethylene with an alkenyl carboxylate and styrene, and especially an ethylene/vinyl acetate copolymer.

In an alternatively preferred embodiment, the at least one cold flow improver (i) is a mixture of at least one copolymer of ethylene with at least one further ethylenically unsaturated monomer (a) with at least one polar nitrogen compound (d). With regard to suitable and preferred cold flow improvers (a) and (d), reference is made to the above remarks.

The at least one solvent (ii) is a solvent for the at least one cold flow improver (i) and is preferably selected from aliphatic and aromatic hydrocarbons and mixtures thereof. What are used are generally solvents/solvent mixtures as are customary for fuel additive packages. Examples thereof are gasoline fractions, kerosene, decane, pentadecane, toluene, xylene, ethylbenzene, or else commercial solvent mixtures such as Solvent Naphtha, Shellsol® AB, Solvesso® 150, Solvesso® 200, Exxsol®, ISOPAR® and Shellsol® D types. It is optionally also additionally possible to use more polar solvents, for example higher alcohols having from 4 to 14 carbon atoms, such as n-butanol, 2-ethylhexanol, decanol, isodecanol or isotridecanol, or higher ethers such as di-n-butyl ether, or esters, which then act as solubilizers.

In a preferred embodiment of the invention, the at least two components to be mixed, as well as components (i) and (ii), also comprise

-   (iii) at least one further fuel oil additive which is selected from     detergent additives, ashless dispersants, demulsifiers, dehazers,     carrier oils, cetane number improvers, metal deactivators, corrosion     inhibitors, antioxidants, lubricity improvers, defoamers, antistats,     stabilizers, color markers, fragrances and mixtures thereof.

The detergent additives are preferably amphiphilic substances which have at least one hydrophobic hydrocarbon radical having a number-average molecular weight (M_(a)) of from 85 to 20 000 and at least one polar moiety which is selected from:

-   (A) mono- or polyamino groups having up to 6 nitrogen atoms, at     least one nitrogen atom having basic properties; -   (B) nitro groups, optionally in combination with hydroxyl groups; -   (C) hydroxyl groups in combination with mono- or polyamino groups,     at least one nitrogen atom having basic properties; -   (D) carboxyl groups or their alkali metal or alkaline earth metal     salts; -   (E) sulfonic acid groups or their alkali metal or alkaline earth     metal salts; -   (F) polyoxy-C2-C4-alkylene moieties which are terminated by hydroxyl     groups, mono- or polyamino groups, at least one nitrogen atom having     basic properties, or by carbamate groups; -   (G) carboxylic ester groups; -   (H) moieties which derive from succinic anhydride and have hydroxyl     and/or amino and/or amido and/or imido groups; and/or -   (I) moieties obtained by Mannich reaction of substituted phenols     with aldehydes and mono- or polyamines.

The hydrophobic hydrocarbon radical in the above detergent additives, which ensures the adequate solubility in the fuel oil, has a number-average molecular weight (M_(n)) of from 85 to 20 000, especially from 113 to 10 000, in particular from 300 to 5000. Typical hydrophobic hydrocarbon radicals, especially in conjunction with the polar moieties (A), (C), (H) and (I), include relatively long-chain alkyl or alkenyl groups, especially the polypropenyl, polybutenyl and polyisobutenyl radical, each having M_(n)=from 300 to 5000, especially from 500 to 2500, in particular from 700 to 2300.

Examples of the above groups of detergent additives include the following:

Additives comprising mono- or polyamino groups (A) are preferably polyalkenemono- or polyalkenepolyamines based on polypropene or conventional (i.e. having predominantly internal double bonds) polybutene or polyisobutene having Mn=from 300 to 5000. When polybutene or polyisobutene having predominantly internal double bonds (usually in the beta- and gamma-position) are used as starting materials in the production of the additives, a possible production route is by chlorination and subsequent amination or by oxidation of the double bond with air or ozone to give the carbonyl or carboxyl compound and subsequent amination under reductive (hydrogenating) conditions. The amines used here for the amination may be, for example, ammonia, monoamines or polyamines, such as dimethylaminopropylamine, ethylenediamine, diethylenetriamine, triethylenetetramine or tetraethylenepentamine. Corresponding additives based on polypropene are described in particular in WO-A-94/24231.

Further preferred additives comprising monoamino groups (A) are the hydrogenation products of the reaction products of polyisobutenes having an average degree of polymerization P of from 5 to 100 with nitrogen oxides or mixtures of nitrogen oxides and oxygen, as described in particular in WO-A-97/03946.

Further preferred additives comprising monoamino groups (A) are the compounds obtainable from polyisobutene epoxides by reaction with amines and subsequent dehydration and reduction of the amino alcohols, as described in particular in DE-A-196 20 262.

Additives comprising nitro groups (B), optionally in combination with hydroxyl groups, are preferably reaction products of polyisobutenes having an average degree of polymerization P=from 5 to 100 or from 10 to 100 with nitrogen oxides or mixtures of nitrogen oxides and oxygen, as described in particular in WO-A-96/03367 and WO-A-96/03479. These reaction products are generally mixtures of pure nitropolyisobutenes (e.g. α,β-dinitropolyisobutene) and mixed hydroxynitropolyisobutenes (e.g. α-nitro-β-hydroxypolyisobutene).

Additives comprising hydroxyl groups in combination with mono- or polyamino groups (C) are in particular reaction products of polyisobutene epoxides obtainable from polyisobutene having preferably predominantly terminal double bonds and Mn=from 300 to 5000, with ammonia or mono- or polyamines, as described in particular in EP-A-476 485.

Additives comprising carboxyl groups or their alkali metal or alkaline earth metal salts (D) are preferably copolymers of C₂-C₄₀-olefins with maleic anhydride which have a total molar mass of from 500 to 20 000 and some or all of whose carboxyl groups have been converted to the alkali metal or alkaline earth metal salts and any remainder of the carboxyl groups has been reacted with alcohols or amines. Such additives are disclosed in particular by EP-A-307 815. Such additives serve mainly to prevent valve seat wear and can, as described in WO-A-87/01126, advantageously be used in combination with customary fuel detergents such as poly(iso)buteneamines or polyetheramines.

Additives comprising sulfonic acid groups or their alkali metal or alkaline earth metal salts (E) are preferably alkali metal or alkaline earth metal salts of an alkyl sulfosuccinate, as described in particular in EP-A-639 632. Such additives serve mainly to prevent valve seat wear and can be used advantageously in combination with customary fuel detergents such as poly(iso)buteneamines or polyetheramines.

Additives comprising polyoxy-C₂-C₄-alkylene moieties (F) are preferably polyethers or polyetheramines which are obtainable by reaction of C₂-C₆₀-alkanols, C₆-C₃₀-alkane-diols, mono- or di-C₂-C₃₀-alkylamines, C₁-C₃₀-alkylcyclohexanols or C₁-C₃₀-alkylphenols with from 1 to 30 mol of ethylene oxide and/or propylene oxide and/or butylene oxide per hydroxyl group or amino group and, in the case of the polyether amines, by subsequent reductive amination with ammonia, monoamines or polyamines. Such products are described in particular in EP-A-310 875, EP-A-356 725, EP-A-700 985 and U.S. Pat. No. 4,877,416. In the case of polyethers, such products also have carrier oil properties. Typical examples of these are tridecanol butoxylates, isotridecanol butoxylates, isononylphenol butoxylates and polyisobutenol butoxylates and propoxylates and also the corresponding reaction products with ammonia.

Additives comprising carboxylic ester groups (G) are preferably esters of mono-, di- or tricarboxylic acids with long-chain alkanols or polyols, in particular those having a minimum viscosity of 2 mm²/s at 100° C., as described in particular in DE-A-38 38 918. The mono-, di- or tricarboxylic acids used may be aliphatic or aromatic acids, and particularly suitable ester alcohols or ester polyols are long-chain representatives having, for example, from 6 to 24 carbon atoms. Typical representatives of the esters are adipates, phthalates, isophthalates, terephthalates and trimellitates of isooctanol, of isononanol, of isodecanol and of isotridecanol. Such products also have carrier oil properties.

Additives comprising moieties derived from succinic anhydride and having hydroxyl and/or amino and/or amido and/or imido groups (H) are preferably corresponding derivatives of alkyl- or alkenyl-substituted succinic anhydride and especially the corresponding derivatives of polyisobutenylsuccinic anhydride which are obtainable by reacting conventional or highly reactive polyisobutene having M_(n)=from 300 to 5000 with maleic anhydride by a thermal route or via the chlorinated polyisobutene. Particular interest attaches to derivatives with aliphatic polyamines such as ethylene-diamine, diethylenetriamine, triethylenetetramine or tetraethylenepentamine. The moieties having hydroxyl and/or amino and/or amido and/or imido groups are, for example, carboxylic acid groups, acid amides of monoamines, acid amides of di- or polyamines which, in addition to the amide function, also have free amine groups, succinic acid derivatives having an acid and an amide function, carboximides with monoamines, carboximides with di- or polyamines which, in addition to the imide function, also have free amine groups, or diimides which are formed by the reaction of di- or polyamines with two succinic acid derivatives. Such fuel additives are described in particular in U.S. Pat. No. 4,849,572.

Additives comprising moieties (I) obtained by Mannich reaction of substituted phenols with aldehydes and mono- or polyamines are preferably reaction products of polyisobutene-substituted phenols with formaldehyde and mono- or polyamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine or dimethylaminopropylamine. The polyisobutenyl-substituted phenols may stem from conventional or highly reactive polyisobutene having M_(n)=from 300 to 5000. Such “polyisobutene-Mannich bases” are described in particular in EP-A-831 141.

For a more precise definition of the fuel additives detailed individually, reference is explicitly made here to the disclosures of the abovementioned prior art documents. Particular preference is given to detergent additives from group (H). These are preferably the reaction products of alkyl- or alkenyl-substituted succinic anhydrides, especially of polyisobutenylsuccinic anhydrides, with amines. It will be appreciated that these reaction products are obtainable not only when substituted succinic anhydride is used, but also when substituted succinic acid or suitable acid derivatives, such as succinyl halides or succinic esters, are used.

Particularly preferred detergent additives are polyisobutenyl-substituted succinimides, especially the imides with aliphatic polyamines. Particularly preferred polyamines are diethylenetriamine, tetraethylenepentamine and pentaethylenehexamine, particular preference being given to tetraethylenepentamine. The polyisobutenyl radical has a number-average molecular weight M_(n) of preferably from 500 to 5000, more preferably from 500 to 2000 and in particular of about 1000.

It is self-evident that the detergent additives can be used alone or in combination with at least one of the aforementioned detergent additives.

Suitable mineral carrier oils are the fractions obtained in crude oil processing, such as brightstock or base oils having viscosities, for example, from the SN 500-2000 class; but also aromatic hydrocarbons, paraffinic hydrocarbons and alkoxyalkanols. Likewise useful is a fraction which is obtained in the refining of mineral oil and is known as “hydrocrack oil” (vacuum distillate cut having a boiling range of from about 360 to 500° C., obtainable from natural mineral oil which has been catalytically hydrogenated under high pressure and isomerized and also deparaffinized). Likewise suitable are mixtures of abovementioned mineral carrier oils.

Examples of synthetic carrier oils are selected from: polyolefins (poly-alpha-olefins or poly(internal olefin)s), (poly)esters, (poly)alkoxylates, polyethers, aliphatic polyether amines, alkylphenol-started polyethers, alkylphenol-started polyether amines and carboxylic esters of long-chain alkanols.

Examples of suitable polyolefins are olefin polymers having M_(n)=from 400 to 1800, in particular based on polybutene or polyisobutene (hydrogenated or unhydrogenated).

Examples of suitable polyethers or polyetheramines are preferably compounds comprising polyoxy-C₂-C₄-alkylene moieties which are obtainable by reacting C₂-C₆₀-alkanols, C₆-C₃₀-alkanediols, mono- or di-C₂-C₃₀-alkylamines, C₁-C₃₀-alkylcyclo-hexanols or C₁-C₃₀-alkylphenols with from 1 to 30 mol of ethylene oxide and/or propylene oxide and/or butylene oxide per hydroxyl group or amino group, and, in the case of the polyether amines, by subsequent reductive amination with ammonia, monoamines or polyamines. Such products are described in particular in EP-A-310 875, EP-A-356 725, EP-A-700 985 and U.S. Pat. No. 4,877,416. For example, the polyether amines used may be poly-C₂-C₆-alkylene oxide amines or functional derivatives thereof. Typical examples thereof are tridecanol butoxylates or isotridecanol butoxylates, isononylphenol butoxylates and also polyisobutenol butoxylates and propoxylates, and also the corresponding reaction products with ammonia.

Examples of carboxylic esters of long-chain alkanols are in particular esters of mono-, di- or tricarboxylic acids with long-chain alkanols or polyols, as described in particular in DE-A-38 38 918. The mono-, di- or tricarboxylic acids used may be aliphatic or aromatic acids; suitable ester alcohols or polyols are in particular long-chain representatives having, for example, from 6 to 24 carbon atoms. Typical representatives of the esters are adipates, phthalates, isophthalates, terephthalates and trimellitates of isooctanol, isononanol, isodecanol and isotridecanol, for example di(n- or isotridecyl) phthalate.

Further suitable carrier oil systems are described, for example, in DE-A-38 26 608, DE-A-41 42 241, DE-A-43 09 074, EP-A-0 452 328 and EP-A-0 548 617, which are explicitly incorporated herein by way of reference.

Examples of particularly suitable synthetic carrier oils are alcohol-started polyethers having from about 5 to 35, for example from about 5 to 30, C₃-C₆-alkylene oxide units, for example selected from propylene oxide, n-butylene oxide and isobutylene oxide units, or mixtures thereof. Nonlimiting examples of suitable starter alcohols are long-chain alkanols or phenols substituted by long-chain alkyl in which the long-chain alkyl radical is in particular a straight-chain or branched C₆-C₁₈-alkyl radical. Preferred examples include tridecanol and nonylphenol.

Further suitable synthetic carrier oils are alkoxylated alkylphenols, as described in DE-A-10 102 913.6.

Preferred carrier oils are synthetic carrier oils, particular preference being given to polyethers.

Suitable corrosion inhibitors are, for example, succinic esters, in particular with polyols, fatty acid derivatives, for example oleic esters, oligomerized fatty acids, substituted ethanolamines and products which are sold under the trade name RC 4801 (Rhein Chemie Mannheim, Germany) or HiTEC 536 (Ethyl Corporation).

Suitable demulsifiers are, for example, the alkali metal or alkaline earth metal salts of alkyl-substituted phenol- and naphthalenesulfonates and the alkali metal or alkaline earth metal salts of fatty acids, and also neutral compounds such as alcohol alkoxylates, e.g. alcohol ethoxylates, phenol alkoxylates, e.g. tert-butylphenol ethoxylate or tert-pentylphenol ethoxylate, fatty acids, alkylphenols, condensation products of ethylene oxide (EO) and propylene oxide (PO), for example including in the form of EO/PO block copolymers, polyethyleneimines or else polysiloxanes.

Suitable dehazers are, for example, alkoxylated phenol-formaldehyde condensates, for example the products obtainable under the tradenames NALCO 7D07 (Nalco) and TOLAD 2683 (Petrolite).

Suitable antifoams are, for example, polyether-modified polysiloxanes, for example the products obtainable under the tradenames TEGOPREN 5851 (Goldschmidt), Q 25907 (Dow Corning) and RHODOSIL (Rhone Poulenc).

Suitable cetane number improvers are, for example, aliphatic nitrates such as 2-ethyl-hexyl nitrate and cyclohexyl nitrate, and peroxides such as di-tert-butyl peroxide.

Suitable antioxidants are, for example, substituted phenols such as 2,6-di-tert-butylphenol and 2,6-di-tert-butyl-3-methylphenol, and phenylenediamines such as N,N′-di-sec-butyl-p-phenylenediamine.

Suitable metal deactivators are, for example, salicylic acid derivatives such as N,N′-disalicylidene-1,2-propanediamine.

Component (iii) is preferably selected from antioxidants, corrosion inhibitors and antistats.

When component (iii) is used in the process according to the invention, the individual additives are used in those amounts customary for such packages in relation to component (i).

When component (iii) is used in the process according to the invention, preference is given to mixing all three components (i), (ii) and (iii) in the dynamic mixer or in the lamination mixer.

Alternatively, in the process according to the invention, preferably only component (i) and component (ii) are mixed in the dynamic mixer or in the lamination mixer.

In the case that only components (i) and (ii) are mixed in the dynamic mixer or lamination mixer used in accordance with the invention, component (iii) can also be incorporated subsequently into the additive mixture obtained in accordance with the invention, for example by customary stirring in or mixing, when the finished additive package is also to comprise component (iii). This would be possible, for example, when the mixing in of component (iii) does not present any particular problems and a homogeneous package which does not have any handling disadvantages can also be obtained by conventional mixing processes.

In the context of the present invention, fuel oils are understood to mean liquid fuels. Suitable fuel oils are gasoline fuels and middle distillates. Middle distillates are preferably selected from diesel fuels, heating oil and turbine fuels.

The heating oils are, for example, low-sulfur or sulfur-rich mineral oil raffinates, or hard coal or brown coal distillates, which typically have a boiling range of from 150 to 400° C. The heating oils are preferably low-sulfur heating oils, for example those having a sulfur content of at most 0.1% by weight, preferably of at most 0.05% by weight, more preferably of at most 0.005% by weight and especially of at most 0.001% by weight. Examples of heating oil include especially heating oil for domestic oil-fired boilers or EL heating oil. The quality requirements for such heating oils are laid down, for example, in DIN 51-603-1 (cf. also Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, vol. A12, p. 617 ff., which is hereby explicitly incorporated by reference).

The diesel fuels are, for example, mineral oil raffinates which typically have a boiling range of from 100 to 400° C. They are usually distillates having a 95% point up to 360° C. or even higher. They may, however, also be so-called “ultra low sulfur diesel” or “city diesel”, characterized by a 95% point of, for example, not more than 345° C. and a sulfur content of not more than 0.005% by weight, or by a 95% point of, for example, 285° C. and a sulfur content of not more than 0.001% by weight.

In addition to the diesel fuels obtainable by refining (of mineral oil), renewable diesel fuels, synthetic diesel fuels and mixtures of all of these diesel fuel types fall under the term “diesel fuels”.

Synthetic fuels generally refer to gasoline and diesel fuels which are obtained from various primary energy sources by the Fischer-Tropsch process. The primary energy carrier is converted first to synthesis gas which is then reacted further catalytically to give the desired fuel type. The type of process determines whether synthetic diesel fuels or else synthetic gasoline fuels are obtained. When coal is used as the primary energy source, reference is made to a CTL fuel (CTL: coal-to-liquid); when natural gas is used, the end product is called GTL fuel (GTL: gas to liquid). When biomass is the starting material, the fuel is a BTL fuel (BTL: biomass-to-liquid).

Renewable fuels are fuels which are obtained from renewable raw materials, especially from plants. These include vegetable oils, biodiesel, bioethanol and also the BTL fuels already mentioned. Bioethanol is used in gasoline engines in particular and therefore does not belong to the renewable diesel fuels, but rather is counted among the renewable gasoline fuels. Biodiesel is generally understood to mean the lower alkyl esters of vegetable oils (or else animal fats), i.e. their C₁-C₄-alkyl esters, in particular their ethyl or methyl esters and especially their methyl esters. In Europe, the most frequently used biodiesel is rapeseed oil methyl ester (RME). Biodiesel is obtained by the transesterification of vegetable oils, which of course consist in particular of glyceryl esters of long-chain fatty acids, with lower alcohols (C₁-C₄ alcohols), especially with methanol, but in some cases also with ethanol.

Preferred diesel fuels are diesel fuels which are obtained by refining, synthetic diesel fuels, the GTL, CTL and BTL diesel fuels, vegetable oils, biodiesel and mixtures of these diesel fuel types.

Suitable turbine fuels, which are also referred to as aviation turbine fuels, jet fuels, aviation fuels or turbo fuels, are, for example, fuels of the Jet A, Jet A-1, Jet B, JP-4, JP-5, JP-7, JP-8 and JP-8+100 designation. Jet A and Jet A-1 are commercially available turbine fuel specifications based on kerosene. The corresponding standards are ASTM D 1655 and DEF STAN 91-91. Jet A and Jet A-1, according to their particular specification, have maximum freezing points of −40° C. and −47° C. respectively. Jet B is a more widely cut fuel based on naphtha and kerosene fractions. JP-4 is equivalent to Jet B. JP-4, JP-5, JP-7, JP-8 and JP-8+100 are military turbine fuels, as used, for example, by the marines and airforce. Some of these names denote formulations which already comprise additives, such as corrosion inhibitors, icing inhibitors, static dissipators, etc. Preferred turbine fuels are Jet A, Jet A-1 and JP 8.

Conventional gasoline fuels are described, for example, in Ullmann's Encyclopedia of Industrial Chemistry, 5th ed., 1990, volume A16, p. 719 ff. Owing to their composition, gasoline fuels have a lower boiling point range and a lower density compared to middle distillates.

The gasoline fuels may either be fuels for gasoline engines in automobiles or aviation gasoline (leaded gasoline fuel with an RON of from 100 to 130).

Preferred fuel oils are middle distillates, preference being given to diesel fuels and heating oil. The diesel fuels may, as already stated, be synthetic (GTL, CTL) or renewable diesel fuels obtainable by refining, or mixtures thereof.

The invention further provides additive mixtures which are obtainable by the process according to the invention. Reference is made to the remarks made above with regard to suitable and preferred measures of the process according to the invention and of the mixture components to be used and of their quantitative ratios.

Finally, the invention provides a fuel oil composition which comprises an inventive additive mixture. Reference is made to the remarks made above with regard to suitable and preferred measures of the process according to the invention, of the mixture components to be used and of their quantitative ratios, and also to suitable and preferred fuel oils.

The fuel oil composition comprises the inventive additive mixture generally in customary amounts, for example in an amount of 10 to 2000 ppm by weight, preferably of 20 to 1000 ppm by weight and especially of 50 to 500 ppm by weight.

By virtue of the use of dynamic mixers or lamination mixers in the process according to the invention, additive mixtures superior to the additive mixtures produced by conventional mixing processes with regard to their handling properties are obtained. The functional properties (for example cold flow-improving properties, such as CP, PP and CFPP of the fuel oils additized with the additive mixtures, or intrinsic CP and PP) are at the same time essentially unchanged. “Essentially unchanged” means that the deviation is at most 10%, preferably at most 5%, more preferably at most 3% and especially at most 1% (compared to additive mixtures which are produced by conventional mixing processes). In particular, the inventive additive mixtures have a reduced lower mixing temperature (LMT), a greater storage stability and/or a better filterability according to the SEDAB test described below, compared to additive mixtures which have been produced by conventional mixing processes. Preferably, at least one of these parameters is improved by at least 10% compared to the prior art additive mixtures. Preferably, all three parameters are improved. More preferably, all three parameters are improved by at least 10% compared to the prior art additive mixtures. When only some of these parameters are improved, the remaining parameters are not worsened or are only insignificantly worsened compared to conventionally produced additive components. “Only insignificantly” means that the particular measurement is worse by at most 5%, preferably by at most 3%. The process according to the invention additionally allows components with very different viscosities or else components which are present in very different proportions in the mixture to be mixed with one another completely and homogeneously and hence additive mixtures which are significantly more homogeneous than mixtures produced by conventional mixing processes to be obtained. The process according to the invention especially allows production of additive mixtures from cold flow improvers in solvents as typically used in additive packages for fuel oils, which possess outstanding handling properties. Cold flow improvers are generally high-viscosity waxes which cannot automatically be incorporated homogeneously into such solvents.

The invention will now be illustrated in detail with reference to the nonlimiting examples which follow.

EXAMPLES 1. Production of the Additive Mixtures

Additive mixtures composed of a cold flow improver and a solvent have been produced and tested with regard to their properties. In all tests, a 50% polymer solution was produced, using an ethylene/vinyl acetate copolymer having a vinyl acetate content of 30% by weight and a viscosity of 310 mm²/s (at 120° C.) as the cold flow improver and Solvent Naphtha as the solvent. The temperature of the polymer supplied and also the mixing temperature was in each case 90° C. in all examples. In all cases, the polymer solution formed was cooled via indirect cooling by means of a spiral heat exchanger (length: 1.8 m; diameter: 8 mm) in a waterbath before the discharge from the system.

Example 1

-   -   Mixer: toothed ring dispersing machine from Kinematica, MT5000         type; speed 20 000 rpm     -   Throughput: 10 kg/h     -   Mean residence time: 19.8 s     -   Discharge temperature: 48° C.

Example 2

-   -   Mixer: toothed ring dispersing machine from Kinematica, MT5000         type; speed 20 000 rpm     -   Throughput: 10 kg/h     -   Mean residence time: 19.8 s     -   Discharge temperature: 59° C.

Example 3

-   -   Mixer: toothed ring dispersing machine from Kinematica, MT5000         type; speed 6000 rpm     -   Throughput: 10 kg/h     -   Mean residence time: 19.8 s     -   Discharge temperature: 59° C.

Example 4

-   -   Mixer: mixing pump from K-Engineering, HMR 040 type; speed 3000         rpm     -   Throughput: 10 kg/h     -   Mean residence time: 3.9 s     -   Discharge temperature: 55° C.

Example 5

-   -   Mixer: mixing pump from K-Engineering, HMR 040 type; speed 3000         rpm     -   Throughput: 10 kg/h     -   Mean residence time: 3.9 s     -   Discharge temperature: 61° C.

Comparative Example 1

-   -   Mixer: static mixer from Sulzer, SMX type, diameter 8 mm, length         to diameter ratio=10     -   Throughput: 9.6 kg/h     -   Mean residence time: 1.4 s     -   Discharge temperature: 52° C.

Comparative Example 2

-   -   Mixer: static mixer from Sulzer, SMX type, diameter 8 mm, length         to diameter ratio=10     -   Throughput: 10 kg/h     -   Mean residence time: 1.3 s     -   Discharge temperature: 49° C.

2. Determination of the Properties of the Additive Mixtures

The filterability and the minimum mixing temperature of the additive mixtures produced above into a fuel oil were determined. In addition, the CFPP (cold filter plugging point) of fuel oils additized with the additive mixtures was determined. Additionally, the CP (cloud point) and the PP (pour point) of the cold flow improvers were determined. The CP was determined to ASTM D 2500, the CFPP in the fuel oil to DIN EN 116 and the PP to ASTM D 97. The storage stability, the minimum mixing temperature (lower mixing temperature; LMT) and the filterability (SEDAB) were determined as described below.

The CFPP was determined at in each case a 400 ppm dosage of the additive mixtures produced above in a fuel oil with the following specification: Winter diesel fuel; Austria; CFPP=−14° C.; CP=−11° C.; density=833.6 kd/m³; IBP=167° C.; FBP=361° C.; 90-20=117° C.; 19.2% paraffins

The storage stability was determined visually. For this purpose, it was examined whether, within the period in question, a phase separation, which can also be manifested in cloudiness, had occurred.

SEDAB Filtration Test (ARAL In-House Method)

For this test, a stainless steel vacuum filtration system (SM 16201 from Sartorius) with a 500 ml filter cup, a 2000 ml suction bottle and a membrane filter (stock number 11304 50 N from Sartorius; diameter 50 mm, pore width 0.8 μm; dried at 90° C. for 30 min and stored under dry conditions) is used.

To remove water, soil and coke constituents, the fuel oil is prefiltered through a fluted filter. 500 ml of the prefiltered fuel oil per test are filled into a 1000 ml mixing cylinder. 500 ppm of the additive mixture are added and then the mixture is stored at room temperature for 16 h. Subsequently, the sample is homogenized by twice tilting the mixing cylinder by 180°. The membrane filter is placed into the filtration system and, with the tap closed, the pressure is adjusted to 200 mbar. The attached filter cup is filled with the homogenized sample (500 ml). The tap is opened and the filtration time is determined.

Samples which are completely filterable within 120 s are considered to be uncritical. Samples which are completely filterable within 120 s are considered as a “PASS”; the filtration time is recorded. Samples for which the filtration time is more than 120 s are considered as a “FAIL”.

Determination of the Minimum Mixing Temperature (LMT)

The minimum mixing temperature is important particularly for those refineries which mix additives unheated into fuel oils or mix additives into unheated fuel oils. When the minimum mixing temperature of the additive is high, there may be filter problems after the unheated mixing.

The minimum mixing temperature was determined by a modified SEDAB filtration test:

For this test, a stainless steel vacuum filtration system (SM 16201 from Sartorius) with a 500 ml filter cup, a 2000 ml suction bottle and a membrane filter (stock number 11304 50 N from Sartorius; diameter 50 mm, pore width 0.8 μm; dried at 90° C. for 30 min and stored under dry conditions) is used.

To remove water, soil and coke constituents, the fuel oil is prefiltered through a fluted filter. 500 ml of the prefiltered and unadditized fuel oil per test are filled into a 1000 ml mixing cylinder and brought to the test temperature. The temperature-controlled fuel oil is admixed with the undiluted additive mixture at 40° C. (500 ppm) and immediately homogenized by gently tilting the mixing cylinder ten times. The membrane filter is placed into the filtration system by the top side of the filter and, with the tap closed, the pressure is adjusted to 200 mbar. The attached filter cup is filled with the homogenized sample (500 ml). The tap is opened and the filtration time is determined.

Samples which are completely filterable within 120 s are considered as a “PASS”; the filtration time at the given temperature is recorded. Samples for which the filtration time is more than 120 s are considered as a “FAIL”; the residual volume still present in the filter cup after 120 s is determined. For such samples, the temperature of the fuel oil is increased by 5° C. and the filtration time is determined again. The temperature increase by 5° C. in each case is repeated until the sample is completely filterable within 120 s; the filtration time at the appropriate temperature is recorded. Conversely, in the case of samples which are completely filterable within 120 s, the temperature of the fuel oil is lowered successively by 5° C. in each case until the sample is no longer completely filterable within 120 s. The temperature should not go below the minimum temperature value of 10° C.

The LMT was determined at a dosage of the additive at 40° C. of 500 ppm in a fuel oil with the following specification:

Diesel fuel; Germany; CFPP=−13° C.; CP=−12.2° C., density=835.5 kg/m³; IBP=206° C.; FBP=343° C.; 90-20=74° C.; 22.6% n-paraffins.

The passage time of the unadditized fuel at 10° C. was 74 s.

The results are listed in the table below.

TABLE Example Passage time¹ [s] Storability² LMT [° C.] CFPP [° C.] PP [° C.] SC³ [%] 1 78 0 30 −21 15 49 2 87 + 30 −22 15 49 3 83 + 30 −21 15 49 4 55 + 25 −23 12 50 5 57 + 25 −24 12 55 Comp. 1 >120 − 35 −22 15 49 Comp. 2 110 − 35 −23 15 50 ¹Filterability according to SEDAB test ²+ = more than 6 months; 0 = 6 months; − = less than 6 months ³SC = solids content; determined by evaporating volatile constituents at elevated temperature and reduced pressure 

1-16. (canceled)
 17. A process for producing additive mixtures for fuel oils, in which at least two components of the additive mixture are mixed in a mixer selected from mixing pumps, wherein the at least two components of the additive mixture comprise (i) at least one cold flow improver and (ii) at least one solvent.
 18. The process according to claim 17, wherein said cold flow improver is selected from (a) copolymers of ethylene with at least one further ethylenically unsaturated monomer; (b) comb polymers; (c) polyoxyalkylenes; (d) polar nitrogen compounds; (e) sulfocarboxylic acids or sulfonic acids or derivatives thereof; (f) poly(meth)acrylic esters; (g) alkylphenol-aldehyde resins; and mixtures thereof.
 19. The process according to claim 17, wherein said at least one cold flow improver comprises (a) at least one copolymer of ethylene with at least one further ethylenically unsaturated monomer.
 20. The process according to claim 18, wherein said at least one further ethylenically unsaturated monomer is selected from alkenylcarboxylic esters, (meth)acrylic esters, styrene, styrene derivatives and olefins other than ethylene.
 21. The process according to claim 18, wherein said further ethylenically unsaturated monomer comprises vinyl acetate.
 22. The process according to claim 19, wherein said at least one cold flow improver also comprises (d) at least one polar nitrogen compound.
 23. The process according to claim 17, wherein said solvent is selected from aliphatic and aromatic hydrocarbons and mixtures thereof.
 24. The process according to claim 17, wherein said at least two components of the additive mixture further comprise (iii) at least one further fuel oil additive which is selected from detergent additives, ashless dispersants, demulsifiers, dehazers, carrier oils, cetane number improvers, metal deactivators, corrosion inhibitors, antioxidants, lubricity improvers, defoamers, antistats, stabilizers, color markers, fragrances and mixtures thereof.
 25. The process according to claim 17, wherein the mean mixing time is at most 120 seconds.
 26. An additive mixture obtained by a process according to claim
 17. 27. A fuel oil composition comprising an additive mixture according to claim
 26. 28. The fuel oil composition according to claim 27, wherein the fuel oil is a middle distillate. 